Engraftment of genetically modified neural stem cells has proved to be an excellent approach to provide various growth factors. For stable and robust expression of VEGF,BAY 73-4506 we transplanted VEGF overexpressing immortalized neural stem cells into the injured spinal cord. Our data showed that transplantation of VEGF overexpressing NSCs stimulated proliferation of glial progenitor cells and increased the number of newly born oligodendrocytes. We also report that the ex vivo delivery of VEGF enhanced angiogenesis and tissue sparing, leading to improved locomotor recovery. The present experiment adopted an ex vivo approach for stable and robust expression of VEGF in the injured spinal cord. As expected, transplantation of VEGF overexpressing NSCs elevated the level of VEGF in the injured spinal cord until 6 weeks after SCI. Furthermore, phosphorylation of the VEGF receptor flk-1, which plays a major role in proliferation of precursor cells, angiogenesis, and neuroprotection,BMS-354825 was markedly enhanced by F3.VEGF grafts. These findings indicate that the ex vivo approach using immortalized NSCs ensured a stable and effective increase of the ambient concentration of VEGF in the injured spinal cord, which would be highly demanding or very costly to achieve by direct infusion of VEGF. As gene delivery vehicles, NSCs exhibit inherent long-distance migratory capabil-ities and a remarkable capacity to integrate with host neural tissue. Especially, immortalized human NSCs have shown excep tional capability to find pathological regions. The majority of F3.VEGF NSCs in this study were also found around the lesion cavities, even though they were injected at 2 mm rostral and caudal to the epicenter. Thus, it is highly likely that F3.VEGF grafts functioned as localized and sustained cellular sources providing VEGF directly to the lesion site. The major finding of this study was that F3.VEGF grafts markedly increased the number of BrdU+ proliferating cells. Approximately 40% of all the proliferating cells were NG2+ cells in all the groups. This percentage is comparable to the data of the previous report that almost half of the acutely dividing cells were NG2 immunoreactive. Other proliferating cells after SCI are thought to encompass macrophages/microglial cells, Schwann cells, mature glial cells, ependymal cells, fibroblasts, and endothelial cells.